Fixed SimpleTexturedOpenGL sample.

Several places in the sample's code were calling Unicode versions of Win32 functions with "multibyte" strings. A few changes were required to fix it.

I added a class "UTFConverter", which handles calls to unicode/multibyte string conversions. This should help minimize the impacts on code change in case C++'s codecvt_utf8 ever changes.

In addition, seveal memory leaks have been found, but these fixes will come in another PR because it goes beyond the scope of this PR.

DevIL.lib was removed in CMakeFiles.txt, as it is unused in the sample.

Here is a list of the changes:

- Fixed MB string calls to Unicode functions.
- Added class UTFConverter to handle string conversions.
- Removed reference to DevIL.lib.
- Fixed compile warnings.

samples/SimpleTexturedOpenGL/CMakeLists.txt

@@ -35,7 +35,7 @@ ADD_EXECUTABLE( assimp_simpletexturedogl WIN32
 
 SET_PROPERTY(TARGET assimp_simpletexturedogl PROPERTY DEBUG_POSTFIX ${CMAKE_DEBUG_POSTFIX})
 
-TARGET_LINK_LIBRARIES( assimp_simpletexturedogl assimp ${OPENGL_LIBRARIES} ${GLUT_LIBRARIES} DevIL.lib )
+TARGET_LINK_LIBRARIES( assimp_simpletexturedogl assimp ${OPENGL_LIBRARIES} ${GLUT_LIBRARIES} )
 
 SET_TARGET_PROPERTIES( assimp_simpletexturedogl PROPERTIES
   OUTPUT_NAME assimp_simpletexturedogl

samples/SimpleTexturedOpenGL/SimpleTexturedOpenGL/src/model_loading.cpp

@@ -21,6 +21,8 @@
 #define STB_IMAGE_IMPLEMENTATION
 #include "contrib/stb_image/stb_image.h"
 
+#include <locale>
+#include <codecvt>
 #include <fstream>
 
 //to map image filenames to textureIds
@@ -75,6 +77,36 @@ GLuint*		textureIds;							// pointer to texture Array
 // Create an instance of the Importer class
 Assimp::Importer importer;
 
+// Used to convert between multibyte and unicode strings.
+class UTFConverter {
+	using UTFConverterImpl = std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t>;
+public:
+	UTFConverter(const char* s) :
+		s_(s),
+		ws_(impl_.from_bytes(s)) {
+	}
+	UTFConverter(const std::string& s) :
+		s_(s),
+		ws_(impl_.from_bytes(s)) {
+	}
+	UTFConverter(const std::wstring& s) :
+		s_(impl_.to_bytes(s)),
+		ws_(s) {
+	}
+	inline const std::string& str() const {
+		return s_;
+	}
+	inline const wchar_t* c_wstr() const {
+		return ws_.c_str();
+	}
+private:
+	static UTFConverterImpl impl_;
+	std::string s_;
+	std::wstring ws_;
+};
+
+typename UTFConverter::UTFConverterImpl UTFConverter::impl_;
+
 void createAILogger()
 {
     // Change this line to normal if you not want to analyse the import process
@@ -120,7 +152,7 @@ bool Import3DFromFile( const std::string& pFile)
 	}
 	else
 	{
-		MessageBox(NULL, ("Couldn't open file: " + pFile).c_str() , "ERROR", MB_OK | MB_ICONEXCLAMATION);
+		MessageBox(NULL, UTFConverter("Couldn't open file: " + pFile).c_wstr() , TEXT("ERROR"), MB_OK | MB_ICONEXCLAMATION);
 		logInfo( importer.GetErrorString());
 		return false;
 	}
@@ -205,7 +237,7 @@ int LoadGLTextures(const aiScene* scene)
 		}
 	}
 
-	int numTextures = textureIdMap.size();
+	const size_t numTextures = textureIdMap.size();
 
 
 	/* array with DevIL image IDs */
@@ -217,13 +249,13 @@ int LoadGLTextures(const aiScene* scene)
 
 	/* create and fill array with GL texture ids */
 	textureIds = new GLuint[numTextures];
-	glGenTextures(numTextures, textureIds); /* Texture name generation */
+	glGenTextures(static_cast<GLsizei>(numTextures), textureIds); /* Texture name generation */
 
 	/* get iterator */
 	std::map<std::string, GLuint*>::iterator itr = textureIdMap.begin();
 
 	std::string basepath = getBasePath(modelpath);
-	for (int i=0; i<numTextures; i++)
+	for (size_t i=0; i<numTextures; i++)
 	{
 
 		//save IL image ID
@@ -268,7 +300,7 @@ int LoadGLTextures(const aiScene* scene)
 		else
 		{
 			/* Error occurred */
-			MessageBox(NULL, ("Couldn't load Image: " + fileloc).c_str() , "ERROR", MB_OK | MB_ICONEXCLAMATION);
+			MessageBox(NULL, UTFConverter("Couldn't load Image: " + fileloc).c_wstr(), TEXT("ERROR"), MB_OK | MB_ICONEXCLAMATION);
 		}
 	}
     // Because we have already copied image data into texture data  we can release memory used by image.
@@ -534,31 +566,31 @@ void KillGLWindow()			// Properly Kill The Window
 	{
 		if (!wglMakeCurrent(NULL, NULL))	// Are We Able To Release The DC And RC Contexts?
 		{
-			MessageBox(NULL, "Release Of DC And RC Failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION);
+			MessageBox(NULL, TEXT("Release Of DC And RC Failed."), TEXT("SHUTDOWN ERROR"), MB_OK | MB_ICONINFORMATION);
 		}
 
 		if (!wglDeleteContext(hRC))			// Are We Able To Delete The RC?
 		{
-			MessageBox(NULL, "Release Rendering Context Failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION);
+			MessageBox(NULL, TEXT("Release Rendering Context Failed."), TEXT("SHUTDOWN ERROR"), MB_OK | MB_ICONINFORMATION);
 		}
 		hRC = NULL;
 	}
 
 	if (hDC && !ReleaseDC(hWnd, hDC))	// Are We able to Release The DC?
 	{
-		MessageBox(NULL, "Release Device Context Failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION);
+		MessageBox(NULL, TEXT("Release Device Context Failed."), TEXT("SHUTDOWN ERROR"), MB_OK | MB_ICONINFORMATION);
 		hDC=NULL;
 	}
 
 	if (hWnd && !DestroyWindow(hWnd))	// Are We Able To Destroy The Window
 	{
-		MessageBox(NULL, "Could Not Release hWnd.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION);
+		MessageBox(NULL, TEXT("Could Not Release hWnd."), TEXT("SHUTDOWN ERROR"), MB_OK | MB_ICONINFORMATION);
 		hWnd = NULL;
 	}
 
-	if (!UnregisterClass("OpenGL", hInstance))	// Are We Able To Unregister Class
+	if (!UnregisterClass(TEXT("OpenGL"), hInstance))	// Are We Able To Unregister Class
 	{
-		MessageBox(NULL, "Could Not Unregister Class.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION);
+		MessageBox(NULL, TEXT("Could Not Unregister Class."), TEXT("SHUTDOWN ERROR"), MB_OK | MB_ICONINFORMATION);
 		hInstance = NULL;
 	}
 }
@@ -566,7 +598,7 @@ void KillGLWindow()			// Properly Kill The Window
 GLboolean abortGLInit(const char* abortMessage)
 {
 	KillGLWindow();									// Reset Display
-	MessageBox(NULL, abortMessage, "ERROR", MB_OK|MB_ICONEXCLAMATION);
+	MessageBox(NULL, UTFConverter(abortMessage).c_wstr(), TEXT("ERROR"), MB_OK|MB_ICONEXCLAMATION);
 	return FALSE;									// quit and return False
 }
 
@@ -594,11 +626,11 @@ BOOL CreateGLWindow(const char* title, int width, int height, int bits, bool ful
 	wc.hCursor		= LoadCursor(NULL, IDC_ARROW);	// Load the default arrow
 	wc.hbrBackground= NULL;							// No Background required for OpenGL
 	wc.lpszMenuName	= NULL;							// No Menu
-	wc.lpszClassName= "OpenGL";						// Class Name
+	wc.lpszClassName= TEXT("OpenGL");		        // Class Name
 
 	if (!RegisterClass(&wc))
 	{
-		MessageBox(NULL, "Failed to register the window class", "ERROR", MB_OK | MB_ICONEXCLAMATION);
+		MessageBox(NULL, TEXT("Failed to register the window class"), TEXT("ERROR"), MB_OK | MB_ICONEXCLAMATION);
 		return FALSE;		//exit and return false
 	}
 
@@ -616,14 +648,14 @@ BOOL CreateGLWindow(const char* title, int width, int height, int bits, bool ful
 		if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
 		{
 			// If The Mode Fails, Offer Two Options.  Quit Or Run In A Window.
-			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
+			if (MessageBox(NULL,TEXT("The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?"),TEXT("NeHe GL"),MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
 			{
 				fullscreen = FALSE;		// Select Windowed Mode (Fullscreen = FALSE)
 			}
 			else
 			{
 				//Popup Messagebox: Closing
-				MessageBox(NULL, "Program will close now.", "ERROR", MB_OK|MB_ICONSTOP);
+				MessageBox(NULL, TEXT("Program will close now."), TEXT("ERROR"), MB_OK|MB_ICONSTOP);
 				return FALSE; //exit, return false
 			}
 		}
@@ -644,8 +676,8 @@ BOOL CreateGLWindow(const char* title, int width, int height, int bits, bool ful
 	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);		// Adjust Window To True Requestes Size
 
 	if (!(hWnd=CreateWindowEx(	dwExStyle,						// Extended Style For The Window
-								"OpenGL",						// Class Name
+								TEXT("OpenGL"),						// Class Name
-								title,							// Window Title
+								UTFConverter(title).c_wstr(),							// Window Title
 								WS_CLIPSIBLINGS |				// Required Window Style
 								WS_CLIPCHILDREN |				// Required Window Style
 								dwStyle,						// Selected WIndow Style
@@ -807,14 +839,14 @@ int WINAPI WinMain( HINSTANCE hInstance,         // The instance
 	if (argv != NULL && argc > 1)
 	{
 		std::wstring modelpathW(argv[1]);
-		modelpath = std::string(modelpathW.begin(), modelpathW.end());
+		modelpath = UTFConverter(modelpathW).str();
 	}
 
 	if (!Import3DFromFile(modelpath)) return 0;
 
 	logInfo("=============== Post Import ====================");
 
-	if (MessageBox(NULL, "Would You Like To Run In Fullscreen Mode?", "Start Fullscreen?", MB_YESNO|MB_ICONEXCLAMATION)==IDNO)
+	if (MessageBox(NULL, TEXT("Would You Like To Run In Fullscreen Mode?"), TEXT("Start Fullscreen?"), MB_YESNO|MB_ICONEXCLAMATION)==IDNO)
 	{
 		fullscreen=FALSE;
 	}
@@ -881,5 +913,5 @@ int WINAPI WinMain( HINSTANCE hInstance,         // The instance
 
 	destroyAILogger();
 	KillGLWindow();
-	return (msg.wParam);
+	return static_cast<int>(msg.wParam);
 }